Luxman 509X, 590AXII, or Gryphon Diablo 300 for B&W 802d3

Have you considered the Audionet Watt?

I have not considered Audionet. I am actually totally unfamiliar with the brand, unfortunately!

Happy Holidays... "Tube-y" you say... Well then, this for solid state...  This is the Int 250 by Pass Labs.  

As for power output, Stereophile reviewed the Int-150 and into 4 ohms, it belted out 284 wpc; based on this, I think it is safe to say that the Int-250 into 4 ohms would make 500 wpc.  That is not too shabby.  

I have considered the Pass Int-250, unfortunately, I can't find a dealer anywhere near me. I know it has received many accolades for performance. 

You might like the Circle Labs A200. Hybrid design with a novel topology; NOS Siemens tubes paired with an extremely short signal path yields an amplifier that sounds remarkably close to a triode amp, but just happens to make 100 watts into 8 ohms/200 in to 4. High damping factor for great bass control. It sounds "alive".

Positive Feedback reviewed it recently here and added it to their list of Writer’s Choice Awards 2021:

Thus far, it has been a challenge to find integrated amplifiers at the sub $10,000 price point that perform like top-tier separate preamplifier/amplifier combinations. Then along comes the Circle Labs A200 integrated amplifier. At $8995 it is pricey, however to get the sheer power, control, and nuanced details that makes the jump into high end, without the bulk, it is a steal!

The Circle Labs A200 is easy on the eyes, too, with very elegant industrial design. Keeping with the theme of simplicity, one of the beautiful aspects of the A200 is that it does not contain peripheral devices such as a DAC or phono stage. This allows the price to stay reasonable, while providing the "meat-and-potatoes" of what an integrated amplifier is: A low noise line stage followed by a powerful amplifier section, with as short of a signal path as possible.

When listening, the minimalist preamplifier section, and proprietary Circle Power technology performs as a well-engineered piece of equipment should. Control, power, and extreme inner detail are all present as one would hear with a top-tier component, or should I say: Components? The Circle Labs A200 truly sounds like a separate specialty line-stage and large power amplifier. It has a hint of romanticism, too, but most seem to enjoy music that airs on the side of romance since we do not listen to test signals. What else can I give than the highest recommendation to a piece that truly embodies the saying, "buy once, cry once."